Why a light color? A dark color can look fabulous in a room with low natural light -- warm, cozy, rich and romantic.

The Hunter-Douglas Silhouette is now available in top down/bottom up. The window casing you have is deep and the shades could be inside mount and look good. Silhouettes have very big headers. http://www.hunterdouglas.com/our-products-detail.jsp?id=1 I would go with a color drape the same tone as the walls but darker. The walls look rather blueish in the photo - maybe due to not using a flash? Some heavy, polyester silk-look would make the area elegant. These come in various colors. http://www.touchofclass.com/product/r114-001.do?code=CMZ08 Here is a link that might be useful: Silhouette

One option would be to turn the main room (5.34 x 4.05 = 21.6m2) into an open kitchen/dining room and use the current kitchen in the extension (2.64 x 1.87 = 4.9m2) into a snug. The current kitchen is on a slightly lower level, 3 steps down from the main room. I’m not sure how to approach the layout as the main room is almost square, the only natural light is on the south-facing side, coming through the entrance door, the window in the main room and the window in the current kitchen. I also need to create a lot of storage space as there isn’t any built in at the moment. Some sort of storage for coats/shoes by the entrance door would be helpful. The entrance door opens to the left and there isn’t any room behind it for coat hooks or a boot bench. Suggestions most welcome.

You will need to get quotes in your area as to cost. But I like windows on 2 walls in bedrooms if possible I t also would be great to know where you plan to put your bed. From what I see I would do 2 windows on the N side with the bed in between and then the E window centered on that wall and maybe made as a trnasom height to ge tthe light without interfering with furniture lay out , Install tat window so it can be opened to gat a nice cross breeze and install motorized blinds if you want blackout .That would also give you light and privacy .